Aims: Phenolphthalein, the active ingredient in many laxatives, was recently found to be a carcinogen in rats and mice. In the female mice, one of the affected sites was the ovary, and the ovarian lesions (stromal cell hyperplasia and stromal cell tumor) were seen at the lowest dose of phenolphthalein used (3,000 ppm in feed, administered continuously for 2 years). This dose is similar to the dose in humans consuming two or more phenolphthalein-containing laxative pills per day, but ovarian cancer risk in relation to phenolphthalein-containing laxatives has not been examined. The purpose of this study was to examine the risk of ovarian cancer in relation to use of phenolphthalein-containing laxatives. Accomplishments: We published the results from our first analysis of ovarian cancer risk in relation to use of phenolphthalein-containing laxatives based on a case-control study conducted by Dr. Ness at the University of Pittsburgh. Additional data have been collected in a second case-control study conducted by Dr. Ruth Peters at the University of Southern California School of Medicine. We also completed other analyses relevant to women's health: an analysis of age at natural menopause in relation to ovarian cancer risk using the combined data from 12 case-control studies provided by the Collaborative Ovarian Cancer Group, an analysis of DDE in relation to bone mineral density in perimenopausal women, and an analysis of menstrual cycle patterns in relation to subsequent risk of developing adult-onset diabetes mellitus.